/*
 * Copyright (C) 2007 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.io;

import java.io.Flushable;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Utility methods for working with {@link Flushable} objects.
 * 
 * @author Michael Lancaster
 * @since 2009.09.15 <b>tentative</b>
 */
public final class Flushables {
    private static final Logger logger = Logger.getLogger(Flushables.class
            .getName());

    private Flushables() {
    }

    /**
     * Flush a {@link Flushable}, with control over whether an
     * {@code IOException} may be thrown.
     * 
     * <p>
     * If {@code swallowIOException} is true, then we don't rethrow
     * {@code IOException}, but merely log it.
     * 
     * @param flushable
     *            the {@code Flushable} object to be flushed.
     * @param swallowIOException
     *            if true, don't propagate IO exceptions thrown by the
     *            {@code flush} method
     * @throws IOException
     *             if {@code swallowIOException} is false and
     *             {@link Flushable#flush} throws an {@code IOException}.
     * @see Closeables#close
     */
    public static void flush(Flushable flushable, boolean swallowIOException)
            throws IOException {
        try {
            flushable.flush();
        } catch (IOException e) {
            logger.log(Level.WARNING,
                    "IOException thrown while flushing Flushable.", e);
            if (!swallowIOException) {
                throw e;
            }
        }
    }

    /**
     * Equivalent to calling {@code flush(flushable, true)}, but with no
     * {@code IOException} in the signature.
     * 
     * @param flushable
     *            the {@code Flushable} object to be flushed.
     */
    public static void flushQuietly(Flushable flushable) {
        try {
            flush(flushable, true);
        } catch (IOException e) {
            logger.log(Level.SEVERE,
                    "IOException should not have been thrown.", e);
        }
    }
}
